1. Field of the Invention
The invention relates in general to a backlight module, and more particularly to a direct backlight module applied in a liquid crystal display with two panels.
2. Description of the Related Art
Liquid crystal displays (LCDs) are widely applied in various electrical products such as personal digital assistants (PDAs), notebook computers, digital cameras, digital camcorders, mobile telephones, computer monitors, liquid crystal televisions, and the like because the technology for manufacturing the LCDs is rapidly developed and the LCDs have the advantages of being light, thin, power-saving and radiation-free. Moreover, a LCD with two panels has even more advantages than two LCDs, such as being lighter, thinner and more economical.
FIG. 1 is a schematic sectional view of a conventional LCD with two panels. Referring first to FIG. 1, a liquid crystal display (LCD) 100 at least includes a first panel 110A, a second panel 110B and a backlight module 120. The second panel 110B is disposed opposite to the first panel 110A and the backlight module 120 is disposed between the first panel 110A and the second panel 110B.
The backlight module 120 includes a light box 121, a first optical device 123A, a second optical device 123B and several light sources 122, such as several cold cathode fluorescent lamps (CCFLs). The light sources 122 are disposed within the light box 121. The first optical device 123A is disposed between the light sources 122 and the first panel 110A, and the second optical device 123B is disposed between the light sources 122 and the second panel 110B. The first optical device 123A and the second optical device 123B both include a diffusing sheet and a prism sheet.
However, the impact and the stresses to the light box 121 become higher as LCDs with larger sizes are more widely used. The hanging centers of the first optical device 123A and the second optical device 123B are not properly supported and could sink and deform. Thus, the distance between the first optical device 123A and the second optical device 123B, H, might be different points therebetween, so that the optical quality of the LCD 100 is badly influenced.